Method of and means for cleaning the surfaces of articles made of silver and other metals.



' To all whom it may concern 1 UNITED STATES PATENT OFFICE. I

J 'AuGUsiUs nosnmsnne or nonnom nnenann;

METHOD or him umnsroacnnanme'rnn suanacns or ARTICLES MADE or SILVER ANDIOTHER'METALS.

no Drawing.

Be it known that--I,"Auousrus a subject of the Kin of Great Britain, and resident of 259 'Hlgh 'Holborn, London, W. 0., England, engineer,'have'invented a certain new and useful Method of and Means for Cleaning the Surfaces of Articles Made of Silver and other Metals, of which the following is a s ecificatiom It hashereto or'e been proposed to clean silver, articles by immersing them in a warm aqueous alkaline solution and bringing-them into contact .with a plate made ofa metal electro-positive with respect to silver (6. g. aluminium), the cleaning being effected by I the nascenthydrogen generated which chemi callyreduces and removes the lfilm of oxid, sulfid, or other reducible salt or salts present on thesurface of the article. In practice, thismethod of cleaning unsatisfactory for the reason that the plate of electro-positive metal speedily becomes oxidized, thus preventing the alkaline reagent from attacking the metal plate. Moreover it is essential that effective mechanical contact between. the

metal plate and the article to .be cleaned should take place and this is impracticable when a number of articles arelto be cleaned at the same time. Finally, the cleaning of the surface is unequal and thebulk of the hydrogen generated is wasted.

The object of the present invention is to v In order to prevent premature change 'obviate these disadvantages.

According .to my invention the electropositive metal is in granular comminuted or pulverulent form so that it will become completely disseminated in the alkaline bath' in excess of the surface exposed to the action of the alkaline solution when a plateof electro-positive metalof equal wei ht is employed. Furthermore, the sub-divided st-ate of the metal, when .it has beenadded tothe alkaline solution, gives rise to numerous intense local chemical reactions which bring about the production of nascent hydrogen.

wherever a particle-of metal is in suspension in said solution. In operation, the article itself'acts as-cathode in the electrolyte con-- stitiited by the alkaline solution, and all the particles of the electro-positive metal con stituteminute anodes which make innumer- Specification of Letters Ratent. Application' filed August as, 1912. Serial n5. 'i 'igisz Rosnnnnne,

.able contactswith the article/to be cleaned Patented Jan. 7, 1913.

and becoming gradually dissolvedset up innur'nerable local .elec'tric circuits each of which possesses exceedingly low resistance owing to the small distance "separating the anode from the cathode of each individual circuit. v

As electro-positive metalI'p refer to employ aluminium as this metal is more active than others in an alkaline solution; but. any other metal .(e. g. magnesium, aluminium, zinc, tin, cadmium) electro-positive with respect to. the surface to be cleaned, may be employed; I may employ as electro-positive metal either a mixture or an alloy of metals (e. g. magnalium). .When a mixture of elect-ro-posit-ive metals is used theymay either be in their elementary i. e. unoxidized state, or the particles of one metal may be coated with adepositgof another metal to form aplurality of galvanic couples. To illustrate what-I mean I may instance galvanic couples constituted by particles of zinc coated with a spongy deposit of copper.

- As the elfect'ro positive metal or mixture of metals or alloy, or-metal covered with a deposit of another metal to form' a couple,'

as the case maybe), is in the coinminuted or pulverulen't state, it can be intimately mixed with the alkaline reagent and the mixture a powder or inblock or made up either as paste form.

of the ingredients forming the mixture may be coated with an inert substancesuch asparaflin, resin orthe like or, whenthe mix-. ture is 'to be made up into a paste-,the ingredients may be mixed with an inert liquid substance such as glycerin. A

The relative proportions of the ingredi ents' may obviously vary within wide limits,

but "I have found that,ifor "cleaning silver for example and when aluminium is used as elect-ropositive metal, one part by weight of aluminium to parts by weight of alkaline reagent will produce goodresults,

As alkaline reagents, alkaline salts (e. g. 5

borax,.-sodium'biborate) sodium or potassiumcarbonate or'caustic alkalis'or alkaline earths mixed with salts-suchas bicarbonates, may be'employed to form an alkaline solution.

- Although 'I vhave only referred to the cleaningof silver articles I would have it understood that my invention may be used for cleaning articlesmade of certain other metals. For example, the tarnish on articles made of nickel, tin and gold may be readily and effectually removed by immersing them in a bath constituted by a mixture of the above mentioned ingredients. The article to be cleaned is allowed to remain in the bath for a length of time depending on the amount of tarnish to beremoved and after withdrawal, is rinsed in water and dried. Claims.

1. The method of cleaning the surface of a metal article which consists in immersing the article in an' aqueous alkaline solution containing a metallic substance electro-posi-' tive in respect of the surface to be cleaned in granularor comminuted form. a

2. The method of cleaning the surface of a metal article which consists in immersing the article in an aqueous alkaline solution containing a plurality of metallic substances electro-positive in respect of the surface to be cleaned in granular or comminuted form.

3. The method of cleaning the surface of a metal article which consists in immersing the article in an aqueous alkaline solution containing a metallicsubstance electro-positive. in respect pf the surface to be cleaned in granular or comminuted form, the individual particles of said metallic substance being coated with a deposit of another metal to form galvanic couples.

4. As a new articleof manufacture for cleaning the surface of a metal article,

a mixture of granular or pulverulent materials including a metallic substance electropositive in respect of the surface to be cleaned and an alkaline substance capable of forming in conjunction with water an aqueous electrolyte.

5; As a new article of manufacture for cleaning the surface of a metal article, a mixture of granular or pulverulent materials including a pluralityof metallic sub-' stances el'ectro-positive in respect of the surface to be cleaned, and an alkaline substance capable of forming in conjunctionwith water an aqueous electrolyte. a,

6. As a new article of manufacture for cleaning the surface of a metal article, a

mixture of granular or pulverulent rnate rials including ametallic substance electro-' positlve 1n respect of the surface to be cleaned and an alkaline substance capable of formlng in conjunction with water an aqueous electrolyte, the individual particles of said metallic substance being coated with a deposit of another metal to form galvanic couples.

7. As a new, article of manufacture for cleaning the surface of a metal article, a mixture of granular or pulverulent materials including a metallic substance electro-positive in respect ofthe surface tobe cleaned coated with an inert substance to prevent premature chemical change, and an alkaline substance capable of forming in conjunction with water .an aqueous electrolyte.

8. As a new article of' manufacture for cleaning the surface of a metal article, a

mixture of granular'or pulverulent material including a plurality of metalhc substances electro-p'ositive in respect of the surface to be cleaned, the-individual particles of said metallic substances being coatedwith an inert substance to prevent premature chemical change, and an alkaline substance capable of forming in conjunction with water an aqueous electrolyte.

9. As a new article of manufacture for cleaning the surface of a metal article, a mixture of' granular or pulverulent materials including a metallic substance electroposit-ive in respect of the surface to be cleaned, the individual particles of which metallic substance being coated with a deposit of another metal to form galvanic couples which themselves'are coated with an inertsubstance to revent' chemical change, and an alkaline su stance capable of forming with water an aqueous electrolyte.

10. As a new article of manufacture for cleaning the surface of a metal article, a mixture of granular or pulverulent materials including a metallic substance electropositive in respectiof the surface to be cleaned, an alkaline substance capable of forming in conjunction with water an aque ous electrolyte, and an inert binding agent.

11. As a new article of manufacturejor cleaning the surface of a inetal art1cle,

rials including a plurality of metallic substances electro-positive in respect of the surface to becleaned, an alkaline substance capable of forming in conjunction with water an aqueous electrolyte, and an inert binding agent.

12. As a new article of manufacture for cleaning the-surface of a metal article, a mixtureof granular or pulverulent materials including a metallic substance electro- -positive in respect of the surface to be cleaned whose individual particles are coated with a deposit of another metal to form galvanic couples, an alkaline substance capable of forming -in conjunction with water an aqueous electrolyte, and an inert binding agent.

13. As a newarticle of manufacture for 105 a mixture of granular or pulverulent matealkaline capable at forming in conjunction with water an aqueous electrolyte, and a binding agent.

14. As a new article of manufacture for cleaning the surfaceof a metal article, a mixture of granular in: pulverulent materials including a plurality of metallic sub stances 'electro-posltive in respect of the surface to be cleaned, theindividual particles o fwhich are coated with an inert solid substance to prevent premature chemical change, an alkalinesub'stance capable of formmg in conjunction with water an 'aqueous electrolyte-and a binding agent.

15. As a new article of manufacture for cleaning the surface of a metal article, a A

mixture of granular or pulverulent materials including a single metal electro-positive in respect'of. the surface to be-cleaned,

the particles of which are coated with a deposit of another metal to, form galvanic couples which themselves are coated with an v inert substance to prevent chemical.

change, an alkaline substance capable, of

forming with water an aqueous electrolyte, a5v 

